Rotating systems similar to a centrifuge typically comprise a housing (i.e., a chassis) , a motor disposed within the chassis, a shaft axially attached at one end to a rotor within the motor such that the shaft is rotatably disposed about a longitudinal axis, and an external rotary body attached to the other end of the shaft. The motor, the shaft, and the rotary body collectively may be referred to as the rotary unit.
In FIG. 1, there is shown a prior art rotating system 10, similar to, for instance, a centrifuge. The rotating system 10 includes, among other things, a shaft 12, a motor 14 attached to one end of the shaft 12 and for rotating the shaft about a longitudinal axis 11, and a rotary body 16, connected to an opposite end of the shaft 12. The prior art rotating system 10 may also include a chassis 18. As can be seen in FIG. 1, although only the motor 14 is shown within chassis 18, the chassis 18 may be designed to accommodate the shaft 12 as well as the rotary body 16. To prevent the motor 14 from moving within the chassis 18 during rotation, prior art rotating systems have employed a variety of designs and mechanisms to secure the motor 14 to the chassis 18. One approach, as illustrated in FIG. 1, is to provide mounting means 19 between a top end of the motor 14 and a top side of the chassis 18.
Generally, when the rotary unit of a rotating system has a perfectly balanced rotor, there is substantially no vibratory motion within the rotating system when the unit is rotating. This is because in a perfectly balanced rotary unit, the axis of rotation of the rotary unit coincides with the unit's geometric longitudinal axis and principal axis of inertia. In contrast, when there is an unbalance in the weight distribution within rotary body, even to a small degree, the principal axis of inertia of the rotary unit is displaced laterally or is rotated with respect to the geometric longitudinal axis. When the axis of rotation does not coincide with the principal axis of inertia, the system gives rise to structure-borne vibration within the rotating system. In many instances, it is not uncommon for the vibration to be transferred from the rotary body, down the shaft, to the motor, and ultimately to the chassis. In the presence of a vibrating chassis, offensive acoustics are often produced.
At present, there are several mechanisms available for reducing structure-borne vibration in an unbalanced rotating system. Mechanisms such as those disclosed in U.S. Pat. Nos. 1,094,589 (Poland), 1,750,016 (Meyer), 2,647,591 (Young), 2,661,620 (Young), 2,693,098 (Young), 2,716,356 (Wiedemann), 2,748,945 (Lodge), 2,827,229 (Blum), 3,692,236 (Livshitz et al.), and 3,958,433 (Bochan) include dampening means between the motor and the chassis. These dampening means, however, are designed only to reduce the vibration of the rotary unit of the respective rotating system. The dampening means are not designed to be situated at a pivot point (i.e., a point about which the rotary unit, when floating freely in one location in space, naturally pivots)of the rotary unit, and hence can neither minimize the transference of vibration from the rotary unit to the chassis nor reduce the occurrence of offensive acoustics produced from the vibrating chassis. By way of example, in the patents to Young, dampening means which utilize spring-biased mechanisms are provided for the attachment of the motor to the chassis at a nodal point (i.e., a point at which the geometric longitudinal axis of the system and the axis of rotation intersect) of the rotating system. However, because the nodal point in a rotating system and its associated vibration often change with respect to a change in the rotational speed, the Young dampening means can only provide restraint against the vibration associated with low rotational speed. As the rotational speed of the system increases, the vibration associated with the higher rotational speed is allowed to occur unopposed. Thus, by utilizing dampening means in connection with a nodal point, at a higher rotational speed, not only does transference of structure-borne vibration to the Young chassis remain, but the occurrence of offensive acoustics may subsequently result within the Young rotating systems.
Accordingly, it is desirable to provide a rotating system and, in addition, a method that would not only minimize the amount of structure-borne vibration transferred to the chassis at any rotational speed, but would further reduce offensive acoustics produced from the structure-borne vibration transferred to the chassis.